1. General Model Information

Name: Pesticide Root Zone Model

Acronym: PRZM3

Main medium: terrestrial
Main subject: hydrology, biogeochemistry
Organization level: ecosystem
Type of model: partial differential equations (finite elements,1D)
Main application:
Keywords: pesticide, root zone, solute transport, agriculture, unsaturated soil, richards equation, convection-dispersion equation, finite element numerics, finite difference numerics, Monte-Carlo-simulation, vapour phase transport, biodegradation, MOC


Center for Exposure Assessment Modeling (CEAM) (EPA)


Carsel, R.F.; Smith, C.N.;Mulkey, L.A.; Dean, J.D.


PRZM (Pesticide Root Zone Model) is a finite-difference model simulates the vertical one-dimensional movement of pesticides in the unsaturated zone within and below the root zone.
The model consists of hydrologic (flow) and chemical transport components to simulate runoff, erosion, plant uptake, leaching, decay, foliar washoff, and volatilization. Pesticide transport and fate processes include advection, dispersion, molecular diffusion, and soil sorption.
The model includes soil temperature effects, volatilization and vapor phase transport in soils, irrigation simulation and a method of characteristics algorithm to eliminate numerical dispersion.
Predictions can be made for daily, monthly or annual output. PRZM allows the user to perform dynamic simulations considering pulse loads, predicting peak events, and estimating time-varying emission or concentration profiles in layered soils.

PRZM2 links two subordinate models in order to predict pesticide fate and transport through the crop root zone, and the unsaturated zone: PRZM and VADOFT. PRZM, VADOFT and SAFTMOD are part of RUSTIC. RUSTIC links these models in order to predict the fate and transport of chemicals to drinking water wells. The codes are linked together with the aid of a flexible execution supervisor (software user interface) that allows the user to build models that fit site-specific situations. This release of PRZM incorporates several features in addition to those simulated in the original PRZM code: specifically, soil temperature simulation, volatilization and vapor phase transport in soils, irrigation simulation, microbial transformation, and a method of characteristics (MOC) algorithm to eliminate numerical dispersion. PRZM is capable of simulating fate and transport of the parent compound and as many as two daughter species.
VADOFT is a one-dimensional finite-element code which solves the Richard's equation for flow in the unsaturated zone. The user may make use of the constitutive relationships between pressure, water content, and hydraulic conductivity to solve the flow equations. VADOFT may also simulate the fate and transport of two parent and two daughter products.
The PRZM and VADOFT codes are linked together with the aid of a flexible execution supervisor that allows the user to build loading models which are tailored to site-specific situations.
In order to perform exposure assessments, the code is equipped with a Monte Carlo pre- and post-processor.

PRZM3 is the most recent version of a modeling system that links two subordinate models--PRZM and VADOFT--in order to predict pesticide transport and transformation down through the crop root and unsaturated zone.

The PRZM3 model system with documentation is available for microcomputer (DOS) systems.
Enhancements to Release 3.0 include algorithms that enable modeling of nitrogen cycle soil kinetic processes with the ability to track nitrogen discharges from a septic tank into the soil environment and movement to groundwater. Additional enhancements enable better simulation of physicochemical processes, increased flexibility in representing agronomic practices, and improved post-processing and data interpretation aids.
A detail listing of all changes between release versions (Release Notes) is also available.

Source of abstract:U.S. EPA CEAM PRZM3 page

II. Technical Information

II.1 Executables:

Operating System(s): DOS available, (Windows based beta release at FOCUS site - see below)


II.2 Source-code:

Programming Language(s):

II.3 Manuals:

Included in INSTALP3.EXE (see Executables)

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

Donigian, A.S. Jr.; Carsel, R.F. 1992. Developing computer simulation models for estimating risks of pesticide use: research vs. user needs. Weed-Technology. 1992, 6: 3, 677-682; Proceedings of a symposium of the Weed Science Society of America held on 4 Feb., 1991, at Louisville, Kentucky, USA ; 9 ref..
Parrish, R.S.; Smith, C.N.; Fong, F.K. 1992 Tests of the pesticide root zone model and the aggregate model for transport and transformation of aldicarb, metolachlor, and bromide. Journal of Environmental Quality. 1992, 21: 4, 685-697; 35 ref..

Strek, H.J . 1998. Fate of chlorsulfuron in the environment. 2. Field evaluations. Pesticide Science.1998, 53: 1, 52-70; 48 ref..
Cogger, C.G.; Bristow, P.R.; Stark, J.D.; Getzin, L.W.; Montgomery, M. 1998. Transport and persistence of pesticides in alluvial soils: I. Simazine. Journal-of-Environmental-Quality.1998, 27: 3, 543-550; 28 ref..
Ma, Q.L.; Wauchope, R.D.; Hook, J.E.; Johnson, A.W.; Truman, C.C.; Dowler, C.C.; Gascho, G.J.; Davis, J.G.; Sumner, H.R.; Chandler, L.D. 1998. GLEAMS, Opus, and PRZM-2 model predicted versus measured runoff from a coastal plain loamy sand. Transactions of the ASAE.1998, 41: 1, 77-88; 53 ref..
Nicholls, P.H. 1995. Simulation of the movement of bentazon in soils using the CALF and PRZM models. Journal of Environmental Science and Health. Part A, Environmental Science and Engineering.1994, 29: 6, 1157-1166; 12 ref..
Zacharias, S.; Heatwole, C.D. 1994. Evaluation of GLEAMS and PRZM for predicting pesticide leaching under field conditions. Transactions of the ASAE.1994, 37: 2, 439-451; 29 ref..
Mueller, T.C. 1994. Comparison of PRZM computer model predictions with field lysimeter data for dichlorprop and bentazon leaching. Journal of Environmental Science and Health. Part A, Environmental Science and Engineering. 1994, 29: 6, 1183-1195; 6 ref..
Sadeghi, A.M.; Isensee, A.R.; Shirmohammadi, A. 1995. Atrazine movement in soil: comparison of field observations and PRZM simulations. Journal of Soil Contamination.1995, 4: 2, 151-161; 21 ref..
Sanders, P.F. 1995. Calculation of soil cleanup criteria for volatile organic compounds as controlled by the soil-to-groundwater pathway:comparison of four unsaturated soil zone leaching models. Journal of Soil Contamination.1995, 4: 1, 1-24; 31 ref..
Trevisan M.; Capri, E.; Re, A.A.M. del; Vischetti, C.; Marini, M.; Businelli, M.; Donnarumma, L.; Conte, E.; Imbroglini, G.; Walker, A. (ed.); Allen, R. (ed.); Bailey, S.W. (ed.); Blair, A.M. (ed.); Brown, C.D. (ed.); Gunther, P. (ed.); Leake, C.R. (ed.); Nicholls, P.H. 1995. Evaluation of pesticide leaching models using three Italian data-sets. Pesticide movement to water. Proceedings of a symposium held at the University of Warwick, Coventry, UK, on 3-5 April 1995. 1995, 269-274; BCPC Monograph No. 62; 12 ref.. (- VARLEACH, PRZM-2, LEACHP and PESTLA)
Trevisan, M.; Capri, E.; del Re, A.A.M. 1993. Pesticide soil transport models: model comparisons and field evaluation. Toxicological and Environmental Chemistry.1993, 40: 1-4, 71-81; 12 ref..

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: Tobias Gabele 09.1997 , Juergen Bierwirth 8.01.2001

Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:47 CEST 2002

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